Pushes the free electrons around a circuit in a direction
Without voltage electrons still move around but this occurs in an random manner

The more voltage we have the more electrons will flow in a direction
Low voltage means low pressure so less electrons flow

Voltage can exist without a current and we can measure it
But we cannot measure the electrical current (Ampere) without any electrons flowing

Voltage is also sometimes referred to as Potential Difference
Voltage tells us how much work can be done by our circuit

Batteries connected in series will provide an boost to the flow of electrons in the circuit
While parallel connection will increase the duration for which the circuit can be powered

Volt is the force required to drive 1 Coulomb through a resistor for 1 Ohm in 1 sec
1 Coulomb = 6.242 * electrons/ sec